The main plot revolves around the Shield Hero who is summoned to a different world. He is initially ostracized and framed. But he gradually overcomes difficulties, forms his own party, and battles against various threats in the new world.
It depends on your language skills and familiarity with the genre. If you're not used to reading web novels or if English (assuming it's translated) isn't your first language, it might be a bit challenging at first. But if you like the story concept, it can be very engaging.
I'm not entirely sure as I haven't read it specifically. But generally, a web novel about a 'hero of the shield' might be about a protagonist who uses a shield in heroic deeds. It could involve battles, quests, and the hero's journey while relying on the shield as a key element, whether for defense or in some unique combat strategies.
The Shield Hero is of course a very important character. Then there's Raphtalia, who becomes a strong ally and friend to the Shield Hero. Filo is another important one. She's a unique and powerful character. And there are also various villains like the other heroes at times who play important roles in the story by creating conflict for the Shield Hero.